This invention relates to a condensate drain for a respiratory air line, and particularly to a drain for an air line of the type that is alternately under high pressure during the patient's inspiration and low pressure during the patient's expiration.
It is common practice to humidify air provided to a patient on a respirator in order to prevent the lungs and other delicate tissues from drying out. However, a significant fraction of the water added to the respiratory air condenses in the respiratory air line. The condensate accumulates in the low point of the respiratory air line, and so much water can accumulate that it actually interferes with the passage of respiratory air to the patient. Various attempts have been made to provide devices that can drain the condensate without interfering with the function of the respiratory line of carrying respiratory air to the patient. Examples of such devices are shown in Eubanks et al., U.S. Pat. No. 3,545,005; Jacobs, U.S. Pat. No. 3,682,166; Togawa, U.S. Pat. No. 4,090,513; Bird, U.S. Pat. No. 4,020,834; Cronenberg, U.S. Pat. No. 4,327,718; Shanks et al., U.S. Pat. No. 4,457,305; and Chokel, U.S. Pat. No. 4,717,403, incorporated herein by reference.
Generally, the previously available devices have suffered from a number of disadvantages. Many of these devices did not properly seal so that respiratory gas would escape with the condensate during the high pressure portion of the respiratory cycle, or condensate could be aspirated back into the respiratory line during the low pressure portion of the respiratory cycle. Many of the devices did not operate continuously, and from time to time had to be emptied. Finally, many of the devices simply did not effectively and efficiently drain the respiratory line, making it difficult for the patient to breath.